Mounting device for exhaust gas re-circulation valve

ABSTRACT

The present invention relates to a mounting device for an exhaust gas re-circulation valve which prevents the overheating, due to high temperature exhaust gas, of a stepping motor powering the opening and closing of the valve and the valve main body of an exhaust gas re-circulation valve which opens and closes the exhaust gas re-circulation passage of an engine. The valve body  201  of the exhaust gas re-circulation valve is buried in a component  100  of the engine having a lower temperature than the exhaust gas. In such a way, the high temperature of the exhaust gas may be absorbed, dispersed and radiated and as a result there is no need to provide a separate cooling structure such as a coolant chamber and the overheating of the stepping motor  300  due to high temperature exhaust gas may be prevented.

FIELD OF THE INVENTION

The present invention relates to a mounting device for an exhaust gasre-circulation valve provided in an exhaust gas recirculation pathway inan internal combustion engine.

BACKGROUND OF THE INVENTION

Diagram 1 is an internal layout diagram of a stepping motor drivenexhaust gas re-circulation valve. The stepping motor is a device forcontrolling the valve by electrical motive force.

In the diagram, reference numeral 1 represents the housing (valve body),and comprises an inlet port 2 connected to the engine exhaust system(not shown), an outlet port 3 connected to the engine air intake system(not shown) and a re-circulation pathway 4. The valve seat 6 ispress-fitted into the re-circulation pathway and prevents the rollpin 13from detaching. 9 is a bush acting as a bearing, 8 is a holder forpreventing the build up of deposits on the bush 9 and is fitted on thesame axis as the valve seat 6 between the housing 1. 5 is a valve whichis disposed in abutment with the valve seat 6 and is secured to thevalve shaft 7 by caulking. The valve shaft 7 extends through the bush 9and a spring holder 10 and washer 50 are fixed to its other end bycaulking. 12 is a spring which is provided between the spring holder 10and the housing 1 in a compressed state with the direction of forcebeing in the direction of valve closure. 14 is a cooling passage forcooling the motor and the body of the valve.

20 is the body of the stepping motor and is mounted on the housing 1 bya mounting screw so that the axes correspond. 22 is a bobbin aroundwhich the coil 23 is entwined, and which is provided with a yoke 24 andyoke 25 providing a magnetic circuit around the outer circumference. 29is a terminal which is electrically connected to the coil 23 and whichforms the connector element with the motor housing 21. 27 is a platewhich shields magnetically the two coil sections. 26 is a platepreventing the seepage of resin into the inner part of the coil when themotor housing is armor molded.

31 is a magnet. 32 is a rotor which protects the magnet 31 and forms astopper 32 b in the axial direction of the motor shaft and the threadedsection 32 a which meshes with the threaded section 33 a of the motorshaft in the inner section. 30 are bearings fitted to both ends of therotor 32. 28 is platespring which pressures the side of the bearing. 33is a reciprocating motor shaft which converts the rotations of the rotor32 to rectilinear motion by the threaded sections 32 a, 33 a. 34 is astopper pin which is press fitted into the motor shaft 33, 41 is a motorbush which functions as a bearing for the motor shaft 33 and preventsrotation around the D hole.

40 is a motor holder disposed between the housing 1 so as to beconcentric with the motor housing 21 and which protects the bearing 30and the motor bush 41. The spring holder 42 and the joint 43 are fixedto the distal end of the motor shaft 33 by caulking. 44 is a springwhich is compressed between the spring holder 42 and the motor holder 40so that the direction of the force is in the direction of valve opening5.

The operation of the valve will be explained on the basis of the forcecorresponding to the position of the valve in diagram 2.

With reference to diagrams 1 and 2, when the valves are opened startingfrom a position of total valve closure, the rotor 32, including themagnet 31, rotates in the direction of valve opening in a step-wisefashion in response to electrical pulses sent from the control unit (notshown) in the terminal 29. The number of steps correspond with thenumber of pulses and constitutes precise open loop control. Thestep-wise rotations are converted into rectilinear motion by thethreaded section 32 a of the rotor 32 and the threaded section 33 a ofthe motor shaft 33. The motor shaft moves in the direction of valveopening (shown in the lower part of the diagram). At this stage, themovement of the motor shaft 33 is assisted by the force of the spring44. At the moment when the joint 43 and the spring holder 10 are inabutment as a result of this motion, since the force of the springs isadded, the necessary force to move the motor becomes the difference ofthe springs. Further movement entails increased load including thespring constant of the springs.

When the valves are closed, the above process is reversed. The rotor 32including the magnet 31 rotates step-wise in the direction of valveclosure in response to: electrical pulses sent from the control unit(not shown) in the terminal 29. At the moment when the joint 43 and thespring holder 10 become detached as the closure process continues, theload of the spring 44 is added to the motor shaft 33 and the load of thespring 12 is added to the valve 5 as a closure force.

A numerical example of the above process will now be discussed. If thesetting of the spring is set using the open valve position as astandard, then the spring 12 in the set position has a load of 2 Kg f,and a spring constant of 0.05 Kg f/mm. The spring 44 in the set positionhas a load of 1.2 Kg f and a spring constant of 0.05 Kg f/mm. If thestroke from motor shaft activation to valve opening is given as 1 mm,and from opened to totally opened as 4.5 mm, then as shown in Diagram 2,the maximum load on the motor at point of activation and point of totalopening is equal to 1.25 Kg f. In addition the force of closure of thevalve is 2 Kg f and is equal to the load in the set position of thespring A12.

Now referring to the conventional organization of the device (withoutthe spring 44), since the load condition of the spring 12 is the same,in order to achieve the same closure force as in the second diagram, theforce generated by the motor must reach a maximum of 2.225 Kg f ( whenthe valve is completely opened).

As conventional exhaust gas re-circulation valves are constructed in theabove manner, although it is possible to cool the valve body and thestepping motor with coolant introduced into the cooling passage 14, thevalve body must be sufficiently large to form the cooling passage 14around the housing 1. Furthermore a pipe is necessary to connect thecoolant passage 14 to the engine coolant system which increases thenumber of necessary parts. The separate coolant system increases thecomplexity of the layout, all of which increases the price.

The present invention is proposed to solve the above problems. It is apurpose of the present invention to provide, without the need for aseparate cooling system, a mounting device for an exhaust gasre-circulation valve which prevents overheating of the valve body andthe stepping motor, which controls the movement of the exhaust gasre-circulation valve, due to high temperature exhaust gas. The inventionalso involves both a reduction in the size of the exhaust gasre-circulation valve and in the costs involved.

It is a further object of the present invention to enable easy mountingof the exhaust gas re-circulation valve on the engine block and toprevent the high temperature of the exhaust gas from being transmittedto the stepping motor.

Further objects include reductions in costs and the use of the inventionin conjunction with a seal in the mounting part which prevents the valveseat from dislodging.

DISCLOSURE OF THE INVENTION

The mounting device for an exhaust gas re-circulation valve of thepresent invention comprises a valve body disposed in connection with theengine exhaust gas re-circulation passage, a valve seat provided in theinterior of the valve body, a valve shaft mounted movably in the axialdirection of said valve body, a valve which is connected to the valveshaft and which moves in the proximal abutting direction of the valveseat when said valve shaft moves in one direction and which moves awayfrom said valve seat when said valve shaft moves in the other directionand a stepping motor which controls the direction of opening and closureof the valve through valve shaft. The valve body is buried in lowtemperature components of the engine such as the water outlet, intakemanifold and throttle chamber.

By burying the valve body of the exhaust gas re-circulation valve in lowtemperature parts of the engine in accordance with the mounting deviceof the exhaust gas re-circulation valve, it is possible to absorb,diffuse and radiate the high temperature of the exhaust gas throughoutthe engine components. As a result, no separate cooling mechanism suchas a coolant chamber is necessary and the components of the engine canprevent the overheating of the stepping motor due to high temperatureexhaust gas.

The mounting device for an exhaust gas re-circulation valve of thepresent invention provides a valve mounting hole in the low temperaturecomponents of the engine, the hole enabling the insertion of the valvebody.

The mounting device for an exhaust gas re-circulation valve of thepresent invention allows for the simple mounting of the exhaust gasre-circulation valve in the engine components by merely inserting thevalve body of the exhaust gas re-circulation valve into the valvemounting hole located in the low temperature engine components.

The mounting device for an exhaust gas re-circulation valve of thepresent invention provides a valve mounting hole proximate to thecooling passage of the engine.

In accordance with the present invention, the engine components arecooled by the engine coolant flowing through engine cooling passage,therefore the placement of the valve body proximate to the coolingpassage prevents the overheating of the valve body due to hightemperature exhaust gas and, to that degree, the overheating of thestepping motor is also prevented. Furthermore the same advantage isobtained in areas of the engine without coolant such as the intakemanifold due to the large volumes of intake air flowing through thebody.

In the present invention, since the engine layout comprises an exhaustgas intake passage and an exhaust gas outlet passage connected to theexhaust gas re-circulation passage, it is possible to re-circulate theexhaust gas smoothly.

The mounting device for an exhaust gas re-circulation valve of thepresent invention provides a seal member on the edge of the aperture ofthe exhaust gas inlet of the valve body which acts both as a sealbetween the engine components and also prevents the valve seat fromdislocating.

Hence by using a single seal member, it is possible to both preventexhaust gas from escaping from between the valve body and the enginecomponents and prevent the dislocation of the valve seat from the valvebody.

SIMPLE EXPLANATION OF THE DIAGRAMS

Diagram 1 is a cross section showing a conventional exhaust gasrecirculation valve.

Diagram 2 is an explanatory view showing the necessary motive force ofthe valve impelling motor.

Diagram 3 is a cross section showing the mounting device for the exhaustgas re-circulation valve according to embodiment 1 of the presentinvention.

Diagram 4 is an enlarged partial cross section of Diagram 3.

PREFERRED EMBODIMENTS OF THE INVENTION

The preferred embodiments of the invention will be explained below withreference to the accompanying drawings.

Embodiment 1

Diagram 3 is a cross section showing the mounting device for an exhaustgas re-circulation valve according to a first embodiment of theinvention. FIG. 4 is an enlarged partial cross section of Diagram 3. Inthe diagrams, reference numeral 100 denotes components of the enginewith a maximum temperature of 120° C. and lower in temperature than theexhaust gas. These components are hereinafter termed “the engine block”and include the sealing block for a water cooled engine, the wateroutlet for engine coolant, the intake manifold and the throttle chamber.

101 is a cooling passage such as an oil passage, water passage or airpassage provided in the engine block 100 for cooling the engine. Thecooling passage 101 is found in conventional engine blocks 100 of watercooled engines. 102 is a valve mounting hole provided proximally to thecooling passage 101 of the engine block 100. 103 is an exhaust gasintake passage provided in the engine block 100 and communicating withthe valve mounting hole 102. The exhaust gas intake passage 103 isconnected to the first side passage (exhaust gas passage)of the exhaustgas re-circulation passage. 104 is an exhaust gas outlet providedsimilarly in the engine block 100 and communicating with the valvemounting hole 102. The exhaust gas outlet 104 is connected to the secondside passage (intake passage) of the exhaust gas re-circulation passage.105 is a seal element provided in the communicating element of the valvemounting hole 102 and the exhaust gas re-circulation passage 103.

200 is an exhaust gas re-circulation valve mounted on the engine block100. 201 is the valve body of the exhaust gas re-circulation valve 200.The valve body 201 is inserted into the valve mounting hole 102 of saidengine block 100. 202 is the exhaust gas re-circulation inlet hole ofthe valve body 201. 203 is the exhaust gas re-circulation outlet hole ofthe valve body 201. 204 is a locking element for fixing the valve seatprovided in the exhaust gas re-circulation inlet hole 202. 205 is avalve seat which is press fitted into said exhaust gas inlet hole 202and is in abutment with the locking element 204. 206 is a seal memberwhich is inserted into said exhaust gas inlet hole 202 and is inabutment with the lower surface of the valve seat 205 and pushes thevalve seat 205 between the locking element 204. The seal member 206 is aflexible member composed of a material having rigidity such as stainlesssteel and has a skirt 206 a bent on its outer peripheral edge.

The skirt 206 a pushes against the seal 105 of the engine block 200 anddue to its flexibility and acts as a seal on the bottom end of the valvebody 201.

Therefore said seal member 206 functions as a seal preventing exhaustgas from escaping between the bottom end of the valve body 201 and theseal 105 of the engine block 100. It also functions as a valve seatsecuring member preventing the valve seat 205 from dislodging from theexhaust gas inlet hole 202 of the valve body 201.

207 is a valve shaft movably mounted in the axial direction of the valvebody 201. 208 is a valve connected to the bottom of the valve shaft 207.209 is a bearing of the valve shaft 207. 210 is a spring seat mounted atthe top end of said valve shaft 207. 211 is a return spring impellingsaid valve shaft 207 via the spring seat 210 in the direction of closureof said valve 205.

300 is a stepping motor controlling the opening and closure of saidvalve 208 through said valve shaft 207. 301 is a motor housing for thestepping motor 300 and is fixed to the top end of the valve body 201through the spacer 302 by a clamp screw 303. 304 is the coil of thestepping motor 300. 305 is the rotor of the stepping motor 300. 306 isthe motor shaft of the stepping motor 300. The rotor 305 and the motorshaft 306 are hinged by a screw.

307 is a spring seat connected to the bottom of said motor shaft 306.308 is an assisting spring interposed between the spring seat 307 andthe spacer 302. The assisting spring 308 impels said motor shaft 306 inthe direction of valve opening and assists in driving the motor.

The operation of the invention will now be explained.

Starting from a position in which the valve is totally closed, when thevalve opening operation commences, the rotor 305, including the magnet310, rotates step-wise in the direction of valve opening in response toelectrical pulses sent from the control unit (not shown) in the terminal309. The number of steps correspond to the number of transmitted pulsesresulting in exact open loop control. The step-wise rotation isconverted into rectilinear motion by the threaded section 305 a of therotor 305 and the threaded section 306 a of the motor shaft 306. As aresult, the motor shaft moves in the direction of valve opening (thedownwards direction in the diagram). The motor shaft 306 is assisted inthis motion by the force of the spring 308. As soon as the joint 311 andthe spring holder 210 are in abutment, since the force of the spring 211is added, the necessary force for moving the motor lies in thedifference between both springs. Subsequent movement results inincreased load to which is added the spring constant of both springs.

In such a way, when the valve 208 opens, the exhaust gas flowing intothe exhaust gas re-circulation passage from the combustion chamber ofthe engine returns to the combustion chamber of the engine taking thefollowing route: from the exhaust gas inlet passage 103 of the engineblock 100 to the exhaust gas inlet 202 of the valve body 201 then intothe valve body 201 then to the exhaust gas outlet 203 of the valve body201 then to the exhaust gas outlet passage of the engine block 100.

Hence the flow of the exhaust gas through the engine block results inthe absorption, dispersion and radiation of the high temperature exhaustgas into the engine block which is of a lower temperature than theexhaust gas. However as the engine block 100 is cooled by coolantflowing through the cooling passage 101, the high temperature of theexhaust gas is not transmitted from the valve body 201 to the steppingmotor 300. Hence it is possible to prevent the overheating of thestepping motor 300 due to the high temperature exhaust gas.

Embodiment 1 as explained above prevents the overheating of the steppingmotor 300 due to high temperature exhaust gas and obviates the need fora separate coolant structure such as the conventional coolant chamber.This is achieved by burying the valve body 201 in the engine block 100which has a lower temperature than the exhaust gas and mounting thestepping motor 300 on the top of the valve body 201 which has the resultof absorbing, dispersing and radiating the high temperature of theexhaust gas into the engine block 100.

Furthermore there is provided a valve mounting hole 102 near the coolingpassage 101 of the engine block 100 and the valve body 201 is buried inthe valve mounting hole 102. Mounting by burying the exhaust gasre-circulation valve in the engine block 100 is easily performed bysimply inserting the valve body 201 in the valve mounting hole 102. Theengine block 100 is cooled by the engine coolant flowing through thecooling passage 101. Since the valve body 201 is maintained in theenvironment of the coolant, the valve body 201 does not becomeoverheated which in turn prevents the overheating of the stepping motor300.

Furthermore, due to the fact that the skirt 206 a of the seal member 206pushes against the seal 105 of the engine block, the skirt 206 afunctions as a seal between the seal 105 of the engine block 100 and thelower border of the valve body 201. This not only prevents exhaust gasfrom escaping from between these two, but also prevents the detachmentof the valve seat 205 as the seal member 206 is in abutment with thelower surface of the valve seat 205.

Industrial Application

As explained above, the exhaust gas re-circulation valve mounting deviceof the present invention provides for the burying of the valve body ofthe exhaust gas re-circulation valve in parts of the engine block havinga lower temperature than the exhaust gas. It is possible to absorb,disperse and radiate the high temperature of the exhaust gas in theengine block without the need for a separate cooling structure such as acoolant chamber. As a result, it is possible to prevent the steppingmotor from overheating due to the high temperature exhaust gas by usingthe engine block in such a way.

What is claimed is:
 1. An exhaust gas re-circulation valve mountingdevice comprising: a valve body operable to be inserted into an exhaustgas re-circulation passage of an engine to radiate high temperatures ofthe exhaust gas through engine components; a valve seat provided insidesaid valve body; a valve shaft mounted movably in an axial direction ofsaid valve body; a valve connected to said valve shaft and housed insaid valve body, said valve moving in an abutting, proximal direction ofsaid valve seat when said valve shaft moves in one direction and movingaway from said valve seat when said valve shaft moves in the otherdirection; and a motor having a motor housing, a coil, a rotor, and amotor shaft controlling an opening and closing of said valve throughsaid valve shaft, wherein said valve body of said exhaust gasre-circulation valve mounting device is buried in components of theengine which have a lower temperature than the exhaust gas, therebyeliminating a need for a separate cooling system in said exhaust gasre-circulation valve mounting device.
 2. An exhaust gas re-circulationvalve mounting device comprising: a valve body operable to be insertedinto an exhaust gas re-circulation passage of an engine to radiate hightemperatures of the exhaust gas through engine components; a valve seatprovided inside the valve body; a valve shaft mounted movably in anaxial direction of said valve body; a valve connected to said valveshaft and housed in said valve body, said valve moving in an abutting,proximal direction of said valve seat when said valve shaft moves in onedirection and moving away from said valve seat when said valve shaftmoves in the other direction; and a stepping motor controlling anopening and closing of said valve through said valve shaft, wherein saidvalve body of said exhaust gas re-circulation valve mounting device isburied in components of the engine which have a lower temperature thanthe exhaust gas, thereby eliminating a need for a separate coolingsystem in said exhaust gas re-circulation valve mounting device.
 3. Theexhaust gas re-circulation mounting device according to claim 2 whereinthe engine component has an exhaust gas inlet and an exhaust gas outletwhich are connected to the exhaust gas re-circulation passage.
 4. Theexhaust gas re-circulation mounting device according to claim 2 whereina valve mounting hole is provided in an engine component and said valvebody is insertedly buried in said valve mounting hole.
 5. The exhaustgas re-circulation mounting device according to claim 4 wherein thevalve mounting hole is provided in a proximate position to those enginecomponents having a cooling passage.
 6. The exhaust gas re-circulationmounting device according to claim 2 wherein a sealing member is mountedon the edge of the aperture of the exhaust gas inlet of the valve body,said sealing member sealing the engine components and preventing thedetachment of the valve seat.
 7. The exhaust gas re-circulation mountingdevice according to claim 6, wherein the seal member further comprises askirt which pushes against a seal of an engine block providing a seal ona bottom end of said valve body.
 8. The exhaust gas re-circulationmounting device according to claim 2, further comprising a first springseat mounted on top of said valve shaft such that a return spring impelssaid valve shaft via said first spring seat.
 9. The exhaust gasre-circulation mounting device according to claim 8, further comprisinga motor shaft having a second spring seat connected to a bottom portionthereof such that an assisting spring impels said motor shaft via saidsecond spring seat.